Froth flotation concentration of ores



Patented June 23, 1936 PATENT OFFICE 2,044,851 mom FLOTATION CONGENTRATION OF ORES ('l'ornelius E. Keller,

signor to Minerals San Francisco, Calif., aa- Separation North American Corporation, New York, N. Y" a corporation of Maryland No Drawing Application her 6, 1932.,

' Serial No. will dC-laimii. (11209-166) This invention relates to the concentration of ores by flotation and is herein illustrated as applied to such method of ore concentration by the eid oi o sulpho compound containing a m phcnyl radical, such as a, henwi ranthate. represented by the formula M-R' where R represents a non-nitrogenous carbon ring compound,

such as a phenyl group, end R represents e metal or hydrogen. It has been iound that the w froth-flotation concentration oi ores may be eflected very economically in the presence of such an agent, since the cunt oi nuinerol-frothing agent required is often considerably reduced from the emount otherwise necessary, and the time required for ositotion of the ore pulp is often considerably reduced as compared, with that reouircd in the absence of such an agent. Moreover; where the new substance is used, the re-- coveries are often more complete or the concentrate is richer in values to the exclusion of normy floatable iron and other gangue, or both of these advnnteges are obtained.

Thisappllcetion is a contlnunticnin part oi my prior applicctlon Be No. 32,577, flied Jannew 20, 1926.

In the examples herein given one substance used was potassium benzyl xanthate,. which is a non-nitrogenous aromatic compound containing asingle phenyl group, and which is a sulphurcontaining aromatic derivative of carbonic acid. This substance was prepared by dissolving potassium hydromde in a small amount of water, adding the resulting solution to benzyl alcohol while stirring, and subsequently adding the M bon disulphide. Molecular proportions of bensyl alcohol, potassium hydroxide andcarbon disulphide were used. yielding a product which appeared to contain a little free benzyl alcohol The resulting potassium benzyl xanthate was 40 soluble in,water, slightly hygroscopic, and gave the characteristic xanthate reactions with metallic salts.

Sodium benzyl xanthate wasalso tested; It

45 was prepared as followsz-Benzyl alcohol was dissolved. in ether, treated with. the requisite amount of metallic sodium to form sodium benzyl alcoholate and the resulting solution mixed with the requisite amount of carbon disulphide to tassium and sodium benzyl xanthates thus pre- 55 pared functioned similarly to the potassium a small amount of benzyl alcohol benzyl xanthate as above A: described. The phenyl sulpho compound in this form of benzyl xanthate was found to be useful in e and neutral pulps with copper ores and with complex ores such as silver-bearing lead-zinc ores.

The following tests were carried on in a Min-' erals separation subaeration spitzkssten testing machine.

Example 1.-Anaconda copper slimes were made into a pulp with the requisite amount oi water and a itated for o. period of five minutes with 0.4 pound oi potassium benzyi xanthate per ton of ore. Then 0.15 pound of pine oil per ton of ore was addedend the agitation continued for a further period of ten minutes. lit was noted that during the first mentioned period of agitation, and before the pine oil Wes edded, apparently due to the fact that both potassium benzyl xanthate end bensyl alcohol were prescut, a large proportion of the copper mineral was floated and the float was relatively tree of iron. The further float obtained upon the addition of pine oil appeared to contain is larger proportion of iron. The whole operation, however, indicated that the potassium bensyl ranthate greatly facilitated the fiotation oi the copper sulphide present to the exclusion oi the iron which was normally floatable. The iron content was determined by inspection. The results in copper concentrate and recovery are shown in the following table:

A parallel test using potassium benzyl xanthate from which all benzyl alcohol had been removed was made and no substantial frothing action could be observed. Upon the further addition oi. the frothiug condition'swere as above described. It wasalso found that the benzyl alcohol alone produced only a small amount of froth with no substantial concentration of mineral. Similar results were obtained with Shattuck-Arizona ore in an alkaline pulp, a rich concentrate being obtained and a tailing which was low in copper content for this particularly refractory ore.

Example 2.--Shattuck-Arizona ore was reground for twenty minutes in a laboratory ball mill with lime, used at the rate of six pounds of calcium oxide per tone of ore. The ground ore 5 was made into a suitable pulp by the addition of water and was agitated for fifteen minutes with 0.2 pound of potassium benzyl xanthate and 0.15 pound of pine oil, both per ton of ore, to form a rougher concentrate. This concentrate was reagitated for five minutes without the addition of further reagents to yield a finished concentrate and a middling. The results are shown in the following table, from which it will appear that there was a large rejection of iron from the concentrate and no objectionable tendency of the iron to build up in the middlings:

Assays Recoveries Wt. Cu Fe Cu Fe 100.0 a 04 39.1 100.0 100.0 13. 2 11 34 37.7 04.0 12.1 15.0 a as 42.0 15.2 16.8 71.2 1.02 38.8 19.0 70.5

In concentrating a lead-zinc-silver ore the results were highly satisfactory and it was found that the amounts required of agents used, and particularly of pine oil, were substantially reduced and that the usual necessity of retreatment of the concentrate was obviated.

Example 3.Suitably ground ore from the nine hundred foot level of the Tennessee mine near Chloride, Arizona, was made into a pump with water and agitated for ten minutes with 0.2 pound of benzyl xanthate and 0.1 pound of hardwood creosote, both per ton of ore, and a leadbearing froth was separated. There was then added 1.4 pounds of water gas tar, 0.1 pound of pine oil, and 0.8 pound of copper sulphate, all per tone of ore, and the pulp was further agitated for fifteen minutes to yield a zinc-bearing froth. The results are shown in the following table:

Assays Recoveries %Wt. Oz. Ag Pb Zn Ag Pb Zn It was found that while potassium benzyl xanthate prepared as above described was fairly stable, nevertheless, when such material, prepared as first above described, was abouta month old, it became somewhat modified in its properties, with the result that it was capable of use without the addition of any other mineral-frothing agent to produce a satisfactory concentration, and was with a mineral-frothing agent to facilitate and also capable of use as an agent which cooperated.

Assays Recoveries Wt. Cu Cu Assays Recoveries Wt. Pb Zn Pb Zn 100.0 8. 3 2. 3 100. 0 100. 0 15. 2 48. 6 13.0 89. 0 86. 8 3. 3 13. 0 9.0 5. 2 13.2 Tails 81. 5 0. 6 No 5. 8 No Other materials such as thiophenol, parathio cresol, benzyl mercaptan, phenyl-ethyl sulphide and the phenyl-ester of ethyl xanthic acid are also capable of use as agents which cooperate with a miner-frothing agent to facilitate and improve fro-th-fiotation concentration.

Example 6.--Utah Copper Co. ore, reground to 65-mesh with 6 pounds of calcium oxide and 0.4

,pound of thiophenol per ton, was made into a pulp with water and agitated with 0.4 pound of cresylic acid all reagents per ton of solids, the cresylic acid being upwards of pure. The froth concentrate was separated and collected. The results are shown in the following table:

Assays Recoveries Wt.% 011% 1 .1% Cu Fe Heads 1.25 1.36 Conc 4.42 25.76 18.5 90.8 43.8 Tails 95.58 .12 .8 9.2 56.2

Example 7.Anaconda table tailings, 65-mesh, were made into a pulp with water and pre-agitated for half a minute in a neutral pulp with 0.32 pound of pine oil and 0.58 pound of benzyl mercaptan, both per ton of solids, and then further agitated to yield a froth-concentrate which was separated for three minutes. The results are shown in the following table:

Cu Recovery made. 1. 28 Concs 7.44 90 l Taili 0. 15

Example 8.Utah Copper Co. ore, reground to 65-mesh with 6 pounds of calcium oxide per ton of solids, was made into a pulp with water and agitated with 0.4 pound of a 20% solution of parathio-cresol in cresylic acid and a further 0.4 pound A satisfactory of cresylic acid, both per ton of solids, which was upwards of 95% pure. The froth concentrate was separated and collected. The results are shown in the following table:

minutes to yield a froth-concentrate which was separated for three minutes. The concentrate was reagitated for two minutes to clean it by separating into a middling and finished concentrate. The results are shown in the following ys Recoveries table. I

% Fe Cu Fe Wt. Cu Recovery .20 1. as to 13.8 89.4 41.6 1 89:4 0:16 17:2

Cu Recovery Hand 0.88 Cnnoq 7. 25 79. 3

, Tails 0.20

Example 10.-The phenyl ester of xanthic acid was prepared by adding amyl nitrite to a solution of aniline hydrochloride in cold acetic acid and precipitating the diazo compound with ether. The precipitate was washed with ether, dried, and dissolved in water cooled with ice. Then, while thus kept cool, an aqueous solution of potassium xanthate was added to make one molecule of potassium exanthate to one of the diazo compound. A yellow compound formed with the evolution of gas, finally forming a yellow oil at the bottom of the solution. This was dissolved in ether, filtered, and the filtered solution washed successively with dilute caustic potash, dilute hydrochloric acid and with water. The resulting red-' dish oily liquid was then used in froth-flotation procedures as follows:

Utah Copper Co. ore of low grade ground to pass 80-mesh, was made into a pulp with water and pre-agitated for one-half minute with 4 pounds of calcium oxide, 0.32 pound of ne oil,

and 0.47 pound of the reddish oily liquid, all per ton of solids, and then further agitated for three The resulr; of the foregoing Examples 6 to 10 compare with a recovery approximating in blank tests 1. e., tests in which there was added no non-nitrogenous aromatic sulpho compound containing a single phenyl group.

Having thus particularly described certain embodiments of my invention what I claim is:

1. The process of concentrating an ore containtaining a mineral value and gangue, which consists in agitating an aqueous pulp of the ore containing benzyl xanthate so as to form a mineralvaiue-bearing froth, and separating the froth.

2. The process of concentrating an ore containing a mineral value and gangue including normally floatable iron, which consists in agitating an aqueous pulp of the ore containing benzyl xanthate so as to form a mineral-value-bearing froth carrying a relatively large amount of a mineral value and a smaller proportion of the normally floatable iron, and separating the froth.

3. The process of concentrating an ore'containing a mineral value and gangue which consists in agitating an aqueous pulp of the ore containing a flotation agent having a formula including a ring the carbon atoms of which are six in number, such ring forming part of a xanthic acid radical, said agitation being so conducted as to form a mineral-value-bearing fioat, and separating the float.

4. The process of concentrating an ore containing a mineral value and gangue which consists CORNELIUS H. KELLER. 

